Análise comparativa das propriedades mecânicas de diferentes parafusos automotivos classe 10.9

Abstract

Bolts are the most used fasteners in the metalworking industry. There are an infinite variety of suppliers and manufacturers due to large applicability. Thus, quality control is important to ensure its mechanical properties in accordance with standards. So, the aim of this study was to compare randomly obtained generic bolts and standard bolts against established quality assurance standards. With regard to the tensile mechanical properties, the results showed that a standardized screw has a maximum resistance stress of 1137.39 ± 18.2 MPa, a lower value than that of a generic screw of 1164.00 MPa ± 32.42. However, the elongation of standardized screws was approximately 14%, a value higher than that of generic screws, around 10%. The Rockwell hardness results (HRC) confirmed that both bolts undergo a tempering and tempering heat treatment, as well observed on the microstructure. And finally, the elemental analysis of the percentage of Carbon-Sulfur showed that both bolts had values within the specified range. In general, there was no discrepancy in the values obtained, inferring, therefore, that although the generic bolts are cheaper, it also has similar properties to standardized bolts.